NONUNIFORM MISFIT DISLOCATION DISTRIBUTIONS IN NANOSCALE THIN-LAYERS

Energetic, dynamic and kinetic reasons leading to the nonuniformity in misfit dislocation (MD) distributions along the nanoscale layer inter faces are considered. It is demonstrated that they are connected with interactions occurring in the defect ensemble in the layer. The energe tic approach is based on the analysis of the total energy density depe ndence on the number of MDs in the MD row. The approach allows to find critical parameters of a system (misfit strain and thickness of layer ) corresponding to the transition between the uniform and nonuniform M D distributions. Analyzing the conditions for surface dislocation sour ces initiation, the dynamic criterion is worked oat. In such a model M D rows generate back stresses which lock the dislocation sources. A th ree-element defect reaction-diffusion scheme is proposed for the analy sis of dislocation kinetics in the nanoscale layers. It is assumed tha t the defect ensemble consists of gliding, climbing and misfit disloca tions. The existence of a critical layer thickness is predicted, above which temporal oscillations in the defect densities appear.